The advent of the computed tomographic scan has opened the possibility of locating, biopsing, and sequentially analyzing masses in previously inaccessible areas. To assess this technique, we have devised projects to prospectively study the capabilities and drawbacks of this technology. Fourteen patients with advanced carcinoma of the cervix have been evaluated preoperatively with good correlation for the presence of retroperitoneal adenopathy. Biopsies under CT guidance have provided adequate tissue in 75% of 25 patients studied. Ovarian carcinomas are being studied prospectively with 92% predictive accuracy. Other studies include serial assessments of other tumors, particularly lung tumors, and tumor volume studies. Further patient entries will provide more meaningful data in all projects described.